I'll answer, since my day-to-day work involves bringing older people out of isolation and helping them return to their social lives. I'm an audioprosthetist. I spend my days answering these questions.
Yes, there's a range of hearing aid technology. A hearing aid is a computer. Take the example of two computers in an electronics store that look exactly the same. If you launch software such as Word while simultaneously surfing the Internet on one computer, it will be difficult to use, whereas you can launch all the software at the same time on the other computer, and it will work well.
A hearing aid contains a computer. A more sophisticated computer will manage sound better. It will certainly lead to a better understanding of speech and better audibility. The software in hearing aids can emphasize “s” and “f” sounds and contain a noise reducer. A range of technology exists.
It's often said that the best and most high-end hearing aids are the closest thing to normal hearing. All the available research and technology is used to manufacture high-end hearing aids. Basically, the latest technology is used to design a machine that most closely matches the human ear.
Unfortunately, not everyone can afford the Ferrari of hearing aids, or the largest and most efficient hearing aid. As a result, there are various forms of hearing aids.
Since I work in the field, I can see the difference between an entry-level hearing aid and a high-end hearing aid. The performance varies according to the quality of the hearing aid. Obviously, it's better to have an entry-level hearing aid than nothing at all. Science has understood for a very long time that it's better to have a hearing aid in each ear than a hearing aid in only one ear. At one time, glasses had only a single lens, but it was quickly understood that we use both eyes to see in three dimensions. It's the same principle for ears.
Yes, there are different qualities. In an ideal, utopian world, everyone would have high-end hearing aids. That would be best. However, unfortunately, that's not the reality. That said, certainly each increase in quality is a small improvement for the patient. We don't disapprove of the fact that there are hearing aids for all budgets because, unfortunately, not everyone can afford high-end hearing aids.